In Beijing, with NOKIA network equipment, I encountered some problems, when manipulate in MPTY, some times, when I send out the CONNECT to pick up the incoming call, but I could not recived the CONNECT ACK. some motorola phones also have this problem,does anyone encouther this problem before with NOKIA network?

At least two cases,
1) A tried to join 3 calls in a MPTY, then make a MT call from B to A, after A disconnect all calss in MPTY, then answer the MT call, I could not receive CONNECT ACK, after I send out CONNECT

2) B-> A, then C-> A, A hold B, answer C, then join them to MPTY, C disconnect A, then make a call agian, A hold B, answer C, join them agian, tried several times, A could not answer C after A hold B(send CONNECT to C, but there is no CONNECT ACK)